DENVER—Authorities said Tuesday that they were pursuing a man who failed to register as a sex offender before he was arrested and accused of killing a mother and her two young children and sexually assaulting her teenage daughter in southern Colorado.

Sheriff’s officials said they were seeking an arrest warrant for Jaacob Vanwinkle, 31, before he was apprehended Sunday night at the Canon City home where the three bodies were found. The victims included a 5-year-old boy, a 9-year-old girl and their 35-year-old mother. The woman’s 15-year-old daughter fled to a neighbor’s house, saying she had been raped.

Vanwinkle had dated the woman and was living in the family’s home, police Sgt. Shannon Byerly said Tuesday. Autopsies were scheduled for Wednesday.

Vanwinkle faces charges of first-degree murder, kidnapping and sexual assault. A judge told him he could face the death penalty if convicted. Vanwinkle has applied for a public defender, but no attorney had been assigned to his case as of Tuesday.

The charges were the latest in a violent criminal history that spans a decade and at least two states.

Vanwinkle had been required to register as a sex offender since 2004, when he was convicted in Indiana of child molestation and other sex crimes involving girls as young as 5 and 7.

After moving from Indiana to Colorado, he was required to register four times a year. He was supposed to report to the sheriff’s office of Colorado’s Fremont County, where Canon City is located, on March 4 but never showed up, Capt. Don Pinover said.

Pinover said the law gives sex offenders a five-day grace period, so a judge would not have signed a warrant until Monday, the day after the slayings. Vanwinkle was also wanted in another Colorado county on suspicion of violating a protection order, Pinover said.

“He was already wanted, and nobody knew where he was,” he said.

Vanwinkle served less than two years of his seven-year sentence and was in and out of prison in Indiana for parole violations and theft. He was released in 2012. Less than two months later, police in Colorado say his pregnant ex-girlfriend told them he beat her. She told officers he tied her wrists with shoe laces, held a pillow over her head and threatened to rape her.

Vanwinkle pleaded guilty to a misdemeanor count of domestic violence and was sentenced to 18 months in Fremont County jail.

Court records show relatives were concerned about Vanwinkle from an early age.

A relative who lived with Vanwinkle told police after his 2004 arrest for child molestation that she wasn’t surprised. The woman told officers “she was afraid something like this was going to happen” because he had “problems with exposing and fondling himself” since he was 16 and arrested in a grocery store parking lot, according to police reports.

Authorities on Tuesday were still investigating what led up to the slayings. Court documents in the case have been sealed.

More in News

A member of a "sophisticated cocaine trafficking conspiracy" was convicted Monday in federal court in Denver of conspiring to distribute, and possessing with intent to distribute, five kilograms or more of cocaine, according to prosecutors.

A man who shot two eighth graders at Deer Creek Middle School in 2010, and was found not guilty by reason of insanity to attempted murder, will not be allowed to leave the Colorado Mental Health Institute's grounds without supervision, according to a Jefferson County District Court ruling.

After the San Francisco Bay Area, metro Denver experienced the biggest apartment rent increases this decade in the country. But plenty of new supply should put future rent gains closer to the national average, according to a new report from RealPage, a real estate research firm.